Gun-barrel-drilling machine.



l. E. PETERSON.

GUN BARREL DRILLING MACHINE.

APPLICATION FILED AUG-23. 1915.

Patented Jan. 9, 1917.

- enlarged longitudinal,

JOSEPH E. PETERSON, OF NORWICH, CON

NECTICUT, ASSIGNOR OF ONE-HALF TO CHARLES A. POOLE, OF NORWICH, CONNECTICUT.

GUN-BARREL-DBILLING MACHINE.

Application filed August 23, 1915.

To all whom it may concern:

Be it known that I, JosEri-r E. PETERSON, a citizen of the United States, residing at Norwich, in the county of New London, in the State of Connecticut, have invented a certain new and useful Improvement in Gun-Barrel-Drilling Machines, of which the following is a specification, reference being had to the accompanying drawings.

This invention relates to that type of machines used in drilling gun barrels, in which the barrel blank is revolved horizontally in suitable bearings while the drill is suitably fed forward, and my immediate object is to provide a thrust bearing for the said blank which will permit it to automatically yield, slightly, whenever the drill pointengages a hard spot in the steel, thus preventing, in most instances, the breaking of the drill point, and also saving the time ordinarily required for removing the broken drill and substituting a sharp one.

My invention also includes a relatively weaker yielding thrust bearing for the other end of the barrel blank, that is to say the end at which the drill enters, for a purpose hereinafter explained in detail.

My invention is illustrated in the annexed drawings, Figure 1 being a side elevation of a boring machine showing generally the arrangement of the supports for the barrel blank and the drill. Fig. 2 is a relatively enlarged detached view of the gun-barrel blank and its supports. Fig. 3 is a further central, sectional, view of the separated parts of the headblock chuck which supports one end of the barrel blank, and Fig. 4: is a similar view of the parts of the support for the other end of said blank. Fig. 5 shows in section, the parts of Fig. 3 assembled and Fig. 6 is a similar (assembled) view of the parts of Fig. t.

Referring to these drawings, the numeral indicates the bed of the machine, upon which bed are mounted a head-block 21, a tail-block 22, (in which the drill 23 is nonrotatably mounted), and a barrel support or chip-block 24, the arrangement of the parts thus far specified being the same as provided in barrel-drilling machines as now commonly providec. The drill feed and the oil teed are also of the ordinary construction and operation, so I have considered it unnecessary to describe them in detail.

Specification of Letters Patent.

Patented Jan. 9, 1917.

Serial No. 46,955.

The head-block spindle 25 is threaded to enga e the internally threaded end portion 26 or a chuck 27 which is chambered as at 23 to receive a stiff spiral spring 29. The threaded opening 26 is relatively less in diameter than the opening 28 thus providing a shoulder against which the inner end portion of the spring abuts (see Fig. 5). After the spring is placed in the chamber 28 a loosely fitting thimble 29 is slipped into said. chamber until it abuts the spring, and the said thimble is then prevented from leaving the chuck by a bushing 30 which is entered in the chuck and secured fixedly therein by means or" a set-screw 31. The thimble 29 is formed with a central opening of a size calculated to receive a gun-barrel blank, the inner end of said central opening being closed by a screw plug 32 against which the barrel blank may abut, and the outer end portion of said central opening is by preference flared as seen in Fig. 5 of the drawings. As I have stated briefly, the thimble 29 is loosely fitted in the chamber 28, the arrangement of thimble and spring being such that under ordinary conditions, the spring will force the thimble into close and constant abutment with the inner end of the bushing 36 but when an unusual endwise load is put upon the barrel blank as, for example, when the drill point strikes a hard spot in the steel, the spring 29 yields and allows the thimble 29 to give sufficiently to prevent the breaking of the drill point.

In Figs. 1 and 6 I have illustrated (both with assembled and separated parts) the support for the other end of the barrel blank, that is to say, the end at which the drill enters. This barrel support includes a chuck shell 33 which is chambered centrally as at 3-1, to receive a loosely fitting bushing 35 which is inserted through a relatively larger chamber 36 the bushing 35 being formed with an integral flange 35 which abuts the end wall of said chamber 36 and thus limits the movement of the bushing in one direction. The bushing 35 is also formed with a relatively smaller extension 36 upon which is mounted a spiral spring 37 and when the bushing is located in its operative position in the shell 33 a centrally bored nut 38 is screwed into the internally threaded end portion of the said shell to prevent the escape of the bushing but permits said bushing to slide lengthwise a limited distance in the shell when suiiicient end thrust is given to the bushing to overcome the resistance of the spring 37, which spring is relatively weaker than the spring 29 first described by me. To prevent the rotation of the bushing I have cut a longitudinal key seat 36 in said bushing to receive the point of a screw 40 which is tapped into the shell 83.

Mounted on the end of the barrel blank (I, is a collar 41 whose outer end portion is adapted to enter the shell 33 and abut the end of the bushing 35. The barrel blank is thus supported endwise between two springs either of which may yield under certain conditions, for example, if the drill strikes a hard spot in the barrel blank, the spring 29 may yield sufiiciently to permit said hard spot to clear the drill point instead of causing the drill point to grab in to the metal and become broken. Mean while the spring 37 will act, by expansion, to cause the bushing 35 to follow up the barrel blank as the latter jumps forward, and the blank is thus kept under tension at all times. As soon as the undue endwise pressure is removed from the blank, the spring 29 overcomes the resistance of the relatively weaker spring 87 and the blank is forced back to its normal position.

Mv described improvement adds very little to the cost of fitting up a drilling machine of the type illustrated and I find by practical demonstration that it effectually prevents, in nearly every instance, the breaking of the cutting lip of the drill when a hard spot in the steel is struck by said drill.

Having thus described my invention, I claim as new and wish to secure by Letters Patent 1 1. In a barrel drilling machine, means for revolubly supporting the ends of a barrel-blank, yielding thrust bearings therefor, and resilient members for cushioning said bearings, of relativelv diflerent resistances.

2. In a barrel drilling machine, means for revolubly supporting a barrel blank, and yielding thrust bearings of relatively different resistance located at the opposite ends of said blank.

JOSEPH E. PETERSON.

tlopies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. C. V 

